usb: dwc2: Allow exiting hibernation from gpwrdn rst detect

usb: dwc2: Allow exiting hibernation from gpwrdn rst detect

When device cable is disconnected core receives suspend
interrupt and enters hibernation. After entering
into hibernation GPWRDN_RST_DET and GPWRDN_STS_CHGINT
interrupts are asserted.

Allowed exit from gadget hibernation from
GPWRDN_RST_DET by checking only linestate.

Changed the return type of "dwc2_handle_gpwrdn_intr()"
function from void to int because exit from hibernation
functions have a return value.

Acked-by: Minas Harutyunyan <Minas.Harutyunyan@synopsys.com>
Signed-off-by: Artur Petrosyan <Arthur.Petrosyan@synopsys.com>
Link: https://lore.kernel.org/r/20210416124723.B6F17A005C@mailhost.synopsys.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>